The mom of tragic Avonte Oquendo specifically warned staff in writing that the severely autistic 14-year-old was prone to running away and needed one-on-one attention at his Queens elementary school, according to a startling new report by city investigators.

“Safety concerns — Please make sure you keep an eye out he likes to run,” mom Vanessa had wrote in a form sent home by the boy’s teacher as the school year started, according to the report issued Thursday by the Special Commissioner of Investigation for the city school system.

“Need 1-1 supervisor will leave the building,” the mom wrote.

But the mother’s warning never reached anyone outside Avonte’s classroom — only the teacher and class paraprofessionals were aware of his propensity to run away, according to the report.

Just weeks later, on Oct. 4, Avonte would bolt from the building. His remains were found washed up on the banks of the East River in Queens on Jan. 16.

The revelation that the mom’s warning never reached administrators or safety officers at P 277 is part of a 12-page report that provides a minute-by-minute chronology of how multiple staffers who could have halted the boy’s escape were either innocently distracted or busy elsewhere at the time.

Avonte’s mom, Vanessa Fontaine.Photo: Matt McDermott

Also at the time, NYPD School Safety Agent Bernadette Perez was manning the front lobby desk when Avonte twice dashed past her unattended, investigators found.

But Perez did not know Avonte or even which of the building’s three schools he attended, and she was busy dealing with visiting parents.

“Twice [Perez] called out “excuse me” to the boy, but he did not respond,” the report says.

[Perez] “could not chase after the student because she was the only school security agent at the main security desk and could not leave her post,” the investigation found. The other school security agent was at lunch.

The form with Avonte’s mother’s warning was still sitting in the boy’s classroom — unknown to administrators or school safety officers — when administrators realized he was missing, according to the report.

It had been “self-created” and sent home to parents by teacher Julie Murray, as a getting-to-know-your-child aid.

School rules had required Murray to get administration approval before sending such “self-created” forms home to parents, and Murray admitted to investigators that she wasn’t aware that such paperwork needed pre-approval.

“Murray explained that she advised the classroom paraprofessionals about the mother’s concerns and took other precautions in the classroom to keep Avonte from running out,” the report said.

“However Murray did not notify the administration about Avonte’s potential to run away,” the report said.